In 1911, King County voters first turned down, then approved plans to build a new structure for county government. The site settled on had once been owned by city founder Henry Yesler.

Architect A. Warren Gould proposed a twenty-three story tower to handle anticipated growth in county functions, but the county commissioners preferred a more modest beginning. Starting in 1914, a five-story steel frame and reinforced concrete structure was built, and dedicated May 4, 1916 as the five-story City-County Building. In 1930,[2] six floors were added, and later a three story 'attic'. Modernization efforts in 1967 added air conditioning and heavily modified the appearance of the building. In 1987, the King County Courthouse was registered as a King County landmark, which limits the style of future remodeling of public areas to restoring the original appearance.